Most Japanese pregnant women do not take the estimated average requirement (EAR) of folate for pregnant women, which is 400 μg/d. Nevertheless, folate deficiencies have not been reported. We examined biomarkers for evaluating the status of folate in pregnant Japanese women. Apparently healthy pregnant Japanese women were cross-sectionally recruited from a private obstetric hospital. We measured nutritional biomarkers of folate in these women, as well as their folate intake. The numbers of subjects were 230 (49, 62, and 81, and 38 in the first (up to 15 wk), second (16-30 wk), and third (over 31 wk) trimesters of pregnancy, and 1 mo after delivery, respectively). Folate intakes (medians) in the first, second, and third trimesters, and 1 mo after delivery were 235±147 (194), 226±83 (218), and 256±85 (254), and 300±105 (305) μg/d, respectively. Folate concentrations in plasma and erythrocytes appeared to be valid indicators for assessing folate status, with cut-off values of 7 nmol/L and 300 nmol/L, respectively. Plasma folate concentrations (medians) in the first, second, and third trimesters, and 1 mo after delivery were 17.6±9.6 (16.7), 12.4±8.3 (9.4), and 12.1±8.4 (9.4), and 10.7±8.9 (7.9) nmol/L, respectively. Each of the folate values was over the cut-off value. Erythrocyte folate concentrations (medians) in the first, second, and third trimesters, and 1 mo after delivery were 358±108 (365), 389±154 (365), and 325±150 (315), and 308±158 (276) nmol/L, respectively. Each of the folate values was near or over the cut-off value. In conclusion, the data obtained demonstrated that the estimated average requirement of folate for pregnant Japanese women was ≈250 μg/d.
A simple and rapid flow injection (FI) method for the determination of retinyl acetate is reported based on its enhancing effect on the luminol-periodate chemiluminescence (CL) system in an alkaline medium. The detection limit (3s×blank) was 8.0×10−8 mol L−1, with an injection throughput of 90 h−1. The method allows linear increase of CL intensity over the retinyl acetate concentration range of 1.0-100×10−7 mol L−1 (R2=0.9996) with relative standard deviations of 2.4% (n=10) for 5.0×10−7 mol L−1. The key chemical and physical variables (reagent concentrations, flow rates, sample volume, and photomultiplier tube (PMT) voltage) were optimized and potential interferences were investigated. The method was successfully applied to human milk, fresh cow's milk and infant milk-based formulas and the results were in good agreement with the previously reported HPLC method. A brief discussion on the possible CL reaction mechanism is also presented.
To determine the rates of cellular NAD+ synthesis and breakdown, incorporation of stable isotope-labeled precursors into NAD+ should be quantified. Although with 2H (D)-labeled precursors [2,4,5,6-D4]nicotinamide ([D4]Nam) and [2,4,5,6-D4]nicotinic acid ([D4]NA), [D3]NAD+ is formed in human cells, why only three of four D atoms from [D4]Nam and [D4]NA are present in NAD+ remains unknown. Using a liquid chromatography-tandem mass spectrometry, we tested the involvement of D/1H (H) exchange at the redox site of NAD+/NADH (C-4 carbon of the pyridine ring) by oxidoreductases exhibiting opposite stereospecificity for the coenzymes in the 1-Da mass decrease in the cellular NAD+ formation. In all cells examined, [Nam-D3]NAD+, but not [Nam-D4]NAD+, was obtained after the incubation with the D4-labeled precursors, whereas [Nam-D4]NAD+, but not [Nam-D3]NAD+, was synthesized from the same precursors with purified recombinant NAD+ biosynthetic enzymes. [D4]Nam group of [Nam-D4]NAD+ was converted to [D3]Nam group via [D4]NADH by in vitro sequential reduction and oxidation with oxidoreductases exhibiting opposite stereospecificity for the coenzymes. Furthermore, using [2,5,6-D3]Nam, which has H instead of D at the C-4 carbon, as a precursor of NAD+ in the cells, the 1-Da mass decrease in the nucleotide was not observed. Based on these observations, we conclude that following the synthesis of [Nam-2,4,5,6-D4]NAD+, cellular redox reactions of NAD+/NADH convert [Nam-2,4,5,6-D4]NAD+ to [Nam-2,5,6-D3]NAD+. Quantification of [Nam-2,5,6-D3]NAD+ and [2,5,6-D3]Nam would successfully determine the rate of the NAD+ turnover and provide clues to understand regulatory mechanisms of cellular NAD+ concentrations.
We reported previously that a single ingestion of an alcohol extract of grains of paradise (GP, Aframomum melegueta), a species of the ginger family, increases energy expenditure (EE) through the activation of brown adipose tissue, a site of sympathetically mediated metabolic theromogenesis. The present study aimed to examine a daily ingestion of GP extract on whole-body EE and body fat in humans. Whole-body EE and body fat content were measured before and after daily oral ingestion of GP extract (30 mg/d) for 4 wk in 19 non-obese female volunteers aged 20-22 y in a single-blind, randomized, placebo-controlled, crossover design. Four-week daily ingestion of GP and a placebo decreased and increased slightly the visceral fat area at the umbilicus level, respectively. The GP-induced change was significantly different from that induced by the placebo (p<0.05), and negatively correlated with the initial visceral fat area (r=−0.64, p<0.01). Neither GP nor placebo ingestion affected subcutaneous or total fat. The daily ingestion of GP, but not the placebo, increased whole-body EE (p<0.05). These results suggest that GP extract may be an effective and safe tool for reducing body fat, mainly by preventing visceral fat accumulation.
Although the intake of carbohydrates is important for the supplementation of energy substrate utilized during exercise, fat oxidation is possibly prevented by an elevation of insulin, and whether or not the timing of the intake of meals affects energy metabolism during exercise has not been clarified. The purpose of this study was to investigate the effect of the timing of the intake of meals taken at different times before exercise on the carbohydrate and fat metabolism during aerobic exercise. The subjects were eight young trained athletes who performed cycling exercise at the lactate threshold (LT) intensity for 60 min. They performed under five conditions consisting of a no-meal (water) trial, and four meal trials that had a normal meal at 1, 2, 3, and 4 h before the exercise. There were no significant changes for any trial in respiratory exchange ratio, or carbohydrate or fat oxidation rates during exercise. The serum insulin level before exercise in the meal trials was more elevated, the shorter the time to the start of the exercise from meal intake. A tendency for higher blood glucose was shown during exercise with a shorter interval time in the meal trials. No alterations were demonstrated for the serum free fatty acids in any of the groups. These results showed that the timing of the pre-exercise meal taken within a 4-h period before exercise did not affect the energy metabolism of the trained subjects during exercise at LT intensity.
The pathogenesis of bone disorders in young male athletes has not been well understood. We hypothesized that bone fragility is caused by low energy availability, due to insufficient food intake and excessive exercise energy expenditure in young male athletes. To examine this hypothesis, we investigated the influence of food restriction on bone strength and bone morphology in exercised growing male rats, using three-point bending test, dual-energy X-ray absormetry, and micro-computed tomography. Four-week-old male Sprague-Dawley rats were divided randomly into the following groups: the control (Con) group, exercise (Ex) group, food restriction (R) group, and food restriction plus exercise (REx) group after a 1-wk acclimatization period. Thirty-percent food restriction in the R and REx groups was carried out in comparison with that in the Con group. Voluntary running exercise was performed in the Ex and REx groups. The experimental period lasted 13 wk. At the endpoint of this experiment, the bone strength of the femurs and tibial BMD in the REx group were significantly lower than those in the Con group. Moreover, trabecular bone volume and cortical bone volume in the REx group were also significantly lower than those in the Con group. These findings indicate that food restriction causes low bone strength and microarchitectural deterioration in exercised growing male rats.
The effects of acute or chronic intake of boysenberry juice or artificial vinegar on blood pressure (BP) and endothelial function were investigated in spontaneous hypertensive rats (SHR). A single administration of boysenberry juice (BJ, equivalent to 0.5 mL/kg body weight) or artificial boysenberry juice vinegar (BJV, equivalent to 0.5 mL BJ and 0.10 g acetic acid/kg body weight) decreased both systolic blood pressure (SBP) and diastolic blood pressure (DBP) significantly. Reductions in SBP of the control group compared with the BJ and BJV groups reached maxima of −16.8±4.3 and −28.4±7.3 mmHg 8 h after administration, respectively. Chronic SBP- and DBP-lowering effects were also observed upon daily feedings of both BJ and BJV at 4 wk. No significant differences were found in SBP or DBP between respective acute and chronic intake of BJ and BJV, except for the decrease in DBP after 4 wk of BJV intake. This suggests that the polyphenol constituents in BJ and BJV likely play a major role in lowering SBP and DBP under these conditions and that acetic acid added to BJ exerts a DBP-lowering effect after 4 wk of BJV intake. The polyphenolic constituents of these beverages might elevate plasma NO concentration via aortic endothelial nitric oxide synthase activation, but the effects of chronic intake on blood pressure might also be at least partly mediated by the renin-angiotensin system. These results may help explain the beneficial effects of boysenberry intake on cardiovascular health, such as reduced blood pressure and improved endothelial function.
Ectopic adipose tissue in skeletal muscle is implicated in the development of insulin resistance, which is frequently induced by abnormal dietary habits such as excessive eating and a high-fat diet. However, the characteristics of ectopic adipocytes are unknown. In this study, we investigated the characteristics of ectopic adipocytes in the skeletal muscle of spontaneously hypertensive corpulent congenic (SHR/NDmc-cp) rats as a model of insulin resistance from excessive eating. SHR/NDmc-cp rats displayed overt insulin resistance with high plasma glucose, insulin, and triacylglycerol concentrations relative to control Wistar-Kyoto (WKY) rats. In contrast, streptozotocin (STZ)-treated WKY rats had high glucose but low insulin concentrations. Ectopic adipocytes were found around blood vessels in the gastrocnemius in SHR/NDmc-cp rats. Areas of perivascular adipocytes and protein expression of resistin were greater in SHR/NDmc-cp rats than in control and STZ-treated WKY rats. The level of the phosphorylated (active) form of endothelial nitric oxide synthase in the gastrocnemius was lower in SHR/NDmc-cp rats than in the other groups. Insulin-resistant SHR/NDmc-cp rats showed enlarged perivascular adipocytes and greater endothelial cell dysfunction in the gastrocnemius.
The brain protein synthesis and the plasma concentration of growth hormone (GH) is sensitive to the dietary γ-aminobutyric acid (GABA) in ovariectomized female rats; however, the role of dietary GABA on biomarkers including nerve growth factor (NGF) and choline acetyltransferase for the function of cholinergic neurons remains unknown in ovariectomized female rats. The purpose of this study was to determine whether the dietary GABA affects the concentration and mRNA level of NGF, and the activity of choline acetyltransferase in the brains of ovariectomized female rats. Experiments were done on two groups of 24-wk-old ovariectomized female rats given 0 or 0.5% GABA added to a 20% casein diet. The concentrations of NGF and activities of choline acetyltransferase in the cerebral cortex and hippocampus, and mRNA level of NGF in the hippocampus increased significantly with the 20% casein+0.5% GABA compared with the 20% casein diet alone. In the hippocampus, the mRNA level of NGF significantly correlated with the NGF concentration (r=0.714, p<0.01). These results suggest that the administration of GABA to ovariectomized female rats is likely to control the mRNA level and concentration of NGF and cause an increase in the activity of choline acetyltransferase in the brains.
Peroxisome proliferator-activated receptor gamma (PPARγ) responds to thiazolidinedione derivatives, which are ligands of PPARγ, and affects insulin resistance. Recently, a PPARγ study reported that in high-fat-diet-induced obesity, the phosphorylation of PPARγ prevented the transcription of specific PPARγ targets that have anti-obesity effects. We previously reported that genetic variants of the fatty acid desaturase were associated with plasma lipid profiles and could contribute to dyslipidemia in Japanese males. The aim of this study was to investigate the anti-obesity effects of PPARγ variants on lipid profiles. One hundred and thirty-eight (138) Japanese males participated in the study. Their serum lipid markers and the fatty acid composition of their red blood cell (RBC) membranes were determined. The stearoyl-CoA desaturase 1 (SCD1) indices were represented as the fatty acid product : precursor ratios. The participants were genotyped for the single-nucleotide polymorphism rs2938392 in the PPARγ gene. The participants' fitness habits were also surveyed by questionnaire. The effects of habitual exercise on the measured lipid parameters were compared in each genotype group. No association between the genotypes in the PPARγ gene and the biochemical data was found. However, the serum triglyceride levels and the SCD1 indices in RBC membranes were significantly higher in the participants who carried the major rs2938392 allele (A/A) and did not habitually exercise than in those who did exercise. These findings indicate that the risk for detrimental lipid profiles in the absence of habitual exercise depends on the PPARγ genotype in Japanese males.